1. Field of the Inventions
The present inventions relate to methods of speech conversion, for example, for use with cochlear implants (artificial cochlear) in which acoustic information is provided to the cochlea in the form of electrical stimulation.
2. Description of the Related Art
Heretofore, cochlear implants have been provided with an electrode having an array of electrodes arranged within the cochlea. These implants discriminate speech from other sounds by sampling sound with a microphone, and dividing the sound into respective frequency bands with a plurality of band pass filters. Some or all of these frequency bands can carry speech.
The sounds from the respective frequency bands, which can include speech, are transmitted to the electrodes corresponding to channels, to thereby generate electrical stimulation pulses. As such, speech and/or other sounds can be transmitted to the cochlea as electrical stimulation pulses.
The speech conversion is carried out by converting the speech information to the stimulation pulses using a speech processor arranged within the cochlear implant. In such a cochlear implant, it is impossible to obtain a faithful sound reproduction relative to actually processed speech signals when the electrodes are simultaneously stimulated. This is because of generation of unsuitable stimulation caused by mutual action between electrode circuits when the electrodes are simultaneously stimulated.
For resolving such a problem, a continuous interleaved sampler (CIS) system has been adopted as the conventional speech converting method in the cochlear implant. In this system, all channels are successively stimulated at a predetermined interval in order to avoid the simultaneous stimulation of channels and thus all speech information is transmitted without any omission. That is, no speech information can be output until it arrives at its order although it is generated simultaneously with other speech information.
Since the CIS is not a known invention disclosed in any publication, there is no information relating to publications of the prior art.
According to the CIS system of the prior art, since all channels are successively stimulated at a predetermined interval, speech can sometimes be output at a timing delayed from that at which the speech is actually generated and thus the regenerated speech can sound unnatural to the patient.